1. Field of the Invention
The present invention generally relates to a method for manufacturing a monolithic ceramic electronic component such as a monolithic capacitor, and to a ceramic green sheet laminating apparatus used for the same manufacturing method. More particularly, the present invention relates to a method for manufacturing a monolithic ceramic electronic component and a ceramic green sheet laminating apparatus that allow a laminate to be obtained by using a long ceramic green sheet and card-like ceramic green sheets.
2. Description of the Related Art
Hitherto, when manufacturing a monolithic ceramic electronic component, firstly inner electrodes have been formed on one main surface of a ceramic green sheet. Then, a plurality of these ceramic green sheets has been laminated to obtain a laminate. The laminate has been fired after cutting, and a ceramic sintered body has been obtained. Outer electrodes have been formed on the outer surface of the ceramic sintered body, and thereby a monolithic ceramic electronic component has been achieved.
The above-described plurality of the ceramic green sheets must be laminated with a high degree of accuracy. Accordingly, methods for laminating ceramic green sheets using a cutting/laminating head have hitherto been proposed.
For example, Japanese Unexamined Patent Application Publication No. 4-2196 discloses a method for cutting a ceramic green sheet and laminating the cut ceramic green sheets using a cutting/laminating head, after delivering a long ceramic green sheet from a roll and forming inner electrodes on the top surface of the ceramic green sheet.
On the other hand, Japanese Unexamined Patent Application Publication No. 6-246730 discloses a method for stacking, one after another, card-like ceramic green sheets that have been cut into a predetermined shape in advance. Specifically, ceramic green sheets which are punched into a specified shape are stored together with a carrier film in a magazine with the cut carrier films facing upward. These ceramic green sheets with the carrier films are moved onto a laminating stage while each of the sheets is held on an adhesion head. The ceramic green sheets are then laminated on the laminating stage.
As disclosed in Japanese Unexamined Patent Application Publication No. 4-2196, in a laminating method using a long ceramic green sheet, cutting and laminating processes are performed after inner electrodes have been formed on the conveyed ceramic green sheet. When a plurality of types of ceramic green sheets are to be laminated, the laminating process becomes very complicated.
For example, when attempting to laminate a plurality of types of ceramic green sheets in which the shape of inner electrodes are different from each other, a device for printing inner electrodes needs to be changed. Alternatively, it is necessary to previously prepare rolls of ceramic green sheets on which mutually different inner electrodes have been formed, to deliver ceramic green sheets from a plurality of rolls, and to thereby perform cutting and laminating operations thereon.
Furthermore, when a plurality of ceramic green sheet rolls are to be prepared, both the number of rolls and the number of conveying equipment increase. This necessitates a large space for laminating ceramic green sheets.
On the other hand, in the method set forth in Japanese Unexamined Patent Application Publication No. 6-246730, since it is essential only that a plurality of types of ceramic green sheets be stored in the magazine in advance, a plurality of types of ceramic green sheets can be laminated within reason. However, in this method, it is necessary to convey ceramic green sheets one after another from the magazine and stack them, thereby making it difficult to realize a high-speed laminating process.
Accordingly, it is an object of the present invention to provide a method for manufacturing a monolithic ceramic electronic component and a ceramic green sheet laminating apparatus that allow a plurality of types of ceramic green sheets to be efficiently laminated, and that enables high-speed of laminating process and a reduction in space for lamination.
In order to achieve the above-described object, the present invention, in a first aspect, provides a method for manufacturing a monolithic ceramic electronic component formed by using a laminate in which a plural types of ceramic green sheets are laminated. This method comprises the step of preparing a delivery roll around which a long first ceramic green sheet supported on a first carrier film is wound, and a card-like second ceramic green sheet; a first laminating step wherein the first ceramic green sheet supported on the first carrier film is delivered from the delivery roll, wherein the first ceramic green sheet is cut by a cutting/laminating head into a predetermined size, and wherein the cut first ceramic green sheet is laminated to the cutting/laminating head; a second laminating step wherein the card-like second ceramic green sheet is cut by the cutting/laminating head into a predetermined size, and wherein the cut second ceramic green sheet is laminated to the cutting/laminating head; the step of forming a laminate by performing each of the first and second steps plural times; and the step of obtaining a sintered body by firing the laminate.
In the first aspect of the present invention, preferably, inner electrodes are formed on the first ceramic green sheet and/or the second ceramic green sheet.
Also, in the first aspect of the present invention, it is preferable that a plurality of types of the card-like second ceramic green sheets be prepared, and that a plurality of types of the second ceramic green sheets be laminated.
The present invention, in a second aspect, provides a ceramic green sheet laminating apparatus used for the above-described method for laminating ceramic green sheets. This apparatus comprises a delivery roll around which a long first ceramic green sheet, which is supported on a first carrier film, is wound; a take-up roll that is disposed at a predetermined distance from the delivery roll, and that takes up the first carrier film delivered from the delivery roll; first conveying member that conveys the first carrier film and the first ceramic green sheet supported thereon, from the delivery roll to the take-up roll; card-like sheet conveying unit on which a card-like second ceramic green sheet is placed; a cutting/laminating head that is disposed between the delivery roll and the take-up roll, that cuts the first and second ceramic green sheets, and that laminates the cut first and second ceramic green sheets to the bottom surface thereof; a head driving source that moves the cutting/laminating head upward and downward, between the position of the cutting/laminating head when it is located above the first or second ceramic green sheet and the position of the cutting/laminating head when it cuts the first or second ceramic green sheet; a second conveying member that moves the card-like sheet conveying unit, between a first position adjacent a position beneath the cutting/laminating head during cutting and laminating operations thereof, and a second position beneath the cutting/laminating head during cutting and laminating operations thereof.
The ceramic green sheet laminating apparatus according to the second aspect of the present invention, preferably, further comprises a sheet lowering member that positions the first carrier film and first ceramic green sheet beneath the card-like sheet conveying unit when the card-like sheet conveying unit is located at the second position.
Also, the ceramic green sheet laminating apparatus according to the second aspect of the present invention, preferably, further comprises a plurality of the card-like sheet conveying units and a plurality of the second conveying member in order to cut and laminate the plurality of types of the second ceramic green sheets.
Moreover, the ceramic green sheet laminating apparatus according to the second aspect of the present invention, preferably, further comprises a sheet rack that stores a plurality of the card-like second ceramic green sheets, and that supplies the ceramic green sheets stored therein to the conveying unit.
The above and other objects, features, and advantages of the present invention will be clear from the following detailed description of the preferred embodiments of the invention in conjunction with the accompanying drawings.